Phase I studies are needed to provide the parameters and characteristics of acute human toxicity, establish a maximally tolerated dose, delineate basic pharmacokinetics, and indicate a starting clinical dose for Phase III trials of the investigational drug. Based on the in vitro and in vivo evidence that vitamin A and its synthetic analogs are active in the neoplasia process and case reports demonstrating the successful chemoprevention of basal cell carcinoma with large doses of the retinoid isotretinoin, a Phase I intramural clinical trial of a promising new oral synthetic retinoid, 4-HPR (N-4-[hydroxyphenyl]-retinamide), has been implemented. This study has the following objectives: Delineate acute human toxicity patterns of orally administered 4-HPR Determine a maximum tolerated/feasible dose (MT/FD) Evaluate the subacute toxicity of the MT/FD for 3 months Observe evidence of any therapeutic effect on specific cutaneous diseases and disorders of keratinization.